This invention relates to combined heat and power systems for buildings.
Such systems comprise a prime mover such as a natural gas-powered internal combustion engine driving an electrical generator and a heat recovery unit recovering waste heat from the engine exhaust and cooling system and possibly the generator and applying such heat to building heating. The generator is used in parallel with external e.g. mains supply to power electrical equipment in the building. The objective of such systems is heating fuel/electricity cost savings on the assumption that even though not all of the fuel consumed by the system is applied directly to building heating, such heat as is not so applied is applied instead to the generation of electricity which is consumed in the building in performing useful tasks and such consumption generally speaking generates heat so that the fuel heats the building indirectly. The heat may be generated deliberately, as by radiant electric heaters or fan heaters, or it may be generated by incandescent lighting or as an unavoidable by-product, as it were, of the consumption of electric power in for example electric motors or electronic equipment, or simply as transmission losses in the building's wiring. At least to some extent, therefore, the electricity produced can be regarded as free, although the capital cost of the generating plant as well as the running and maintenance costs have to be reckoned with. Account has to be taken, also, of the heating effect of the electricity consumed in a normal building in the absence of a combined heat and power system, which must reduce the amount of fuel needed to be consumed for heating the building.
Nevertheless, substantial advantages and cost savings could accrue from building combined heat and power systems, although for various reasons such systems proposed hitherto have not in general been attractive enough to justify the trouble and expense of installation and operation.
The present invention provides improved combined heat and power systems for buildings which can have substantially improved performance, ease of operation and lower installation and running costs than existing proposed systems.